December 28, 2011

Fixing the Ecotones Sound Sleep Machine

For about a year now, I've owned and used an Ecotones Duet sound sleep machine. Now-a-days it has been rebranded as the Ecotones Sound + Sleep, new name, same thing. For a better look at the device and to read some reviews, check it out on amazon.com.

I've been very happy with the device, no real complaints. However, about 8 months into owning it, it just stopped working. When it was plugged in, there were no lights, and no response to any button presses. The thing was bricked. I hypothesized that some of the internal electronics had gotten fried. I don't expect today's made-in-china electronics to last 10 years, but only 8 months for a $100 purchase is not acceptable. Luckily, when I checked the manual, it stated that there was a 1 year warranty.

I put off calling the support phone number for a long time. I was not looking forward to an hour of waiting on the phone to get the chance to talk to someone who would ask me questions like "did you plug it in?". Much to my surprise, when I called, a human answered within a few rings. He did walk me through some power cycle diagnostics and a factory reset of the unit. However when the troubleshooting process was over, he apologized for my trouble, and said they would send a new unit out to me the next day. I was expecting to have to send my existing unit in for repair, but to get a brand new unit with just a phone call? That's standing by your product. Well done Adaptive Sound Technologies. I was told to dispose of my existing device in an "environmentally safe manner".

As with all broken electronics, if it's headed for the trash, it never hurts to open it up, and see what's inside. Maybe there is a burnt out component that can be replaced with a little solder. If nothing else, I figured, I could recycle the speaker inside.

When I disassembled the device, there wasn't a lot to it, just a tweeter speaker driver, a woofer speaker driver, and a single circuit board:

The use of the standard SD card is interesting. It appears they are storing their firmware and sound recordings on the SD card, rather then some expensive flash chip.

I checked the board for any obviously burnt out resisters, capacitors, etc. Everything seemed fine. Then I checked the AC/DC wall plugin adaptor, which said it is a 5.0V, 1.2A. When checked against a multimeter, it was putting out the appropriate voltage, both by itself, and when under load while plugged into the circuit board. No problems there.

Then I noticed an interesting thing. When I removed the 1 GB SD card from the board, and applied power, the various LEDs would blink in a rhythmic pattern. This tells me the board wasn't necessarily bricked, but that there might be a problem with the SD card.

I placed it in my computer's card reader, to see what was on it. Nothing. The computer didn't even acknowledge the card was there. I couldn't even format it. The card was fried.

So this means, if I could just replace the bad 1 GB SD card, maybe I could revive the broken device. But where could I get a replacement SD card with the appropriate files on it...

The answer is, of course, I was being sent one in the mail. When my replacement device arrived, I opened it up, and took a look at the circuit board. It looked essentially the same as the previous one, however it said version 1.1 on it (the previous said version 1.0) and it used a micro SD card (also 1 GB) instead of a standard size card. I extracted the micro SD card, put it in a full size adaptor, and placed it in the defective board. It worked!

The next step was to see what was on this card. I placed it in my computer's card reader, and saw that it had a single file:

With any luck, all I would need to do is copy this file to a new 1 GB SD card, and I would be in business. However, it didn't go that smoothly. The first time I tried it, I had a SD card that was formatted with FAT32, and upon closer inspection, the working micro SD card from the new device appeared to be formatted with FAT16. Even after reformatting the card to FAT16 and re-copying the image file, I couldn't get the board to work with my newly created card.

I just couldn't figure it out. It should be working. Finally I decided to make a bit-for-bit copy of the working SD card. And here are the steps I took to do that.

First, I used an Apple Macbook, however any Unixy computer will do, Linux included.

Now If I had two SD card readers, I could have just copied the data from one card to the other card directly. However since I only had one available, I had to first copy the data from the good card to my computer, then swap cards in the reader, and copy the data from the computer file to the new card. The first step is to copy the data from the working card to the computer. I figured out the SD card file descriptor was at /dev/disk1. When I first tried this, I did so with the disk mounted, and that didn't that didn't work. So I had to have the card reader and disk plugged in, but not mounted.

I already happened to be located in the /tmp directory, where the file was created. If I hadn't been, I could get there with the command "cd /tmp". Once there, I can confirm the existence of the file with the command "ls".